Aromatic Ylide‐Stabilized Carbocyclic Silylene

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

“…Kira and co-workers were the first to report a carbocyclic silylene -a dialkylsilylene 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl (70) as early as 1999 [66]. From our own group, we recently reported the syntheses of aromatic phosphorus ylide-stabilised carbocyclic silylenes, (71a and 71b) [67], and even more recently Iwamoto and co-workers reported another rare example of a silylene in this class (72) [68], similar to the seminal example by Kira (Fig. 7).…”

“…(For an excellent review on silylene 70 and its reactivity up until 2007, see: [72].) This has enabled vast insights into the reactivity and behaviour of silylenes of this class towards a plethora of small molecule activation reactions, or interesting [67] with permission from the authors) chemical transformations. We will now highlight some selected reactivity investigations of silylene 70 that have appeared in recent years.…”

Cyclic Amino(Ylide) Silylene: A Stable Heterocyclic Silylene with Strongly Electron‐Donating Character

“…[6][7][8][9][10] Only af ew exceptions with an unsymmetrical pattern have recently been reported, namely the acyclica mino(silyl) and amino(boryl) silylenes (G [11] and H [12] ), which are stabilized by p-a nd s-donating substituents.B oth compounds clearly show an ambiphilic reactivity that allows the activation of small molecules such as H 2 .T ot he best of our knowledge, as table silylene featuring two different p-donating groups remains elusive.Out of all the possibilities,wewere interested in an amino/ylide substitution pattern for the stabilization of heterocyclic silylenes (I). [8] In order to tame the reactivity of the silylene by adjusting its basicity,wetargeted the amino(ylide) silylene I,w hich combines ap hosphonium ylide function with al ess-donating amino group.I ti sw orth noting that the related heterocyclic carbene J is by far the most strongly donating carbene ligand for transition metals. [8] In order to tame the reactivity of the silylene by adjusting its basicity,wetargeted the amino(ylide) silylene I,w hich combines ap hosphonium ylide function with al ess-donating amino group.I ti sw orth noting that the related heterocyclic carbene J is by far the most strongly donating carbene ligand for transition metals.…”

“…This signal appears considerably downfield relative to that in NHSi chemical shifts (78-112 ppm), [3] but in asimilar range as in the bis-ylide-stabilized silylene D (213 ppm) [8] or silicon dithiolate E (285 ppm). This signal appears considerably downfield relative to that in NHSi chemical shifts (78-112 ppm), [3] but in asimilar range as in the bis-ylide-stabilized silylene D (213 ppm) [8] or silicon dithiolate E (285 ppm).…”

Synthesis and characterization of 1,1-dihalogenated cyclopentasilanes

“…These and other tetrylenes [32,33] have been synthesized by reductive dehalogenation. Other examples have shown that the type of halogen (Cl vs. Br) can lead to a different outcome of the dehalogenation reaction, resulting in either silylenoids or rearrangement products of silylenes [34].…”